Circuit boards are extremely prolific in all types of electrical equipment, such as computers, radio and video transmitters/receivers, telecommunication devices, appliances and so forth. Such boards, and the equipment housing the boards, are used by business, government, consumers, and others. Thus, the fabrication of such circuit boards, as well as the attachment of components to such circuit boards, has itself become an immensely large industry. The present invention involves an improved method and apparatus for constructing such circuit boards having an improved identification marking apparatus.
FIG. 1 illustrates one very popular circuit board designated generally at 10. Circuit board 10 includes a surface 12, and an edge 14 extending around the perimeter of the board. Although shown as rectangular, it should be noted that board 10 may be of any shape to accommodate specifications which, for example, may relate to the equipment within which board 10 will be installed. Circuit board 10 also includes various manufacturer's identifiers designated 16a, 16b, 16c, and 16d. Identifiers 16a-16d are often formed on surface 12 using a silkscreening process. These identifiers typically indicate information about the board such as the particular manufacturer, the board dimensions and so forth.
Circuit board 10 supports electrical components 17 attached to the board at least in part by an automated assembly machine. As known in the art, such machines are operable to quickly select from a plurality of machine-compatible components, and place the selected component on the circuit board. As an example, one popular automated assembly machine is a surface mount technology ("SMT") machine known in the art. As known in the SMT art, circuit board 10 includes a conductive configuration having surface conductors known as pads 18, and accessible from surface 12. Electrical components 17 are physically and electrically connected to pads 18 underlying each corresponding component as described below. Although not visible in FIG. 1, pads 18 are further interconnected underneath surface 12 by conductive members known in the art as tracks. The tracks permit pads 18 to electrically conduct with one another, thereby allowing electrical components connected to pads 18 to electrically connect to other such components. The shape and dimensions of pads 18 as illustrated are included merely by way of example. For purposes of illustration, only a few electrical components 17 are depicted; however, it should be understood that typically the entire span of pads 18 are connected to, and covered by, such components 17. Further, it should be understood that any shape and/or dimension may be used for pads 18 and the tracks connecting them, and such shape typically depends on the electrical components to be attached to board 10. Pads 18 are labeled in various locations throughout FIG. 1 to indicate that various conductors may be further coupled to one another by the underlying tracks, or may be disconnected from one another; in either case, the layout of pads 18 accommodates the particular circuitry and functionality to be attached to board 10.
Solder paste (not shown) is deposited over pads 18 so that electrical components 17 may thereafter be affixed to the paste and, hence, to circuit board 10. Thereafter, the SMT machine attaches numerous components to board 10. Particularly, the SMT machine selects each component from an array of SMT-compatible components. For example, components attached to reels of tape are often accessible to the SMT machine. The machine removes the selected component from its respective reel, and places it on circuit board 10 in an area of the solder paste. Accordingly, the solder paste temporarily retains the component 17 in contact with its corresponding pads 18 until subsequent processing. Note that the SMT machine can approach component placement times on the order of 25000 parts per hour, and with tolerances on the order of 0.006 inch. After the component is placed against the paste the board is heated and subsequently cools, causing the solder paste to correspondingly flow and harden, thereby adhering the components in place.
Because of its numerous uses and functions, it is desirable to label a circuit board to identify one or more of its characteristics. For example, once circuitry is affixed to the circuit board, the overall board provides certain functionality and, hence, an identifier(s) may be added to the board to denote its functionality. As another example, as the circuitry on a circuit board is revised, it is common in the industry to include, on the board, an indication of the version of the board. As yet another example, an identifier may be added to the board to denote the apparatus in which the board is to be placed. Still other identification purposes will be known, or become apparent, to a person skilled in the art. For purposes of this invention, any or all of these identification purposes of the circuit board are referred to as the board's "operational characteristics."
Under current SMT technology, a circuit board's operational characteristics are indicated directly on surface 12 of the circuit board and consist of one or more alphanumeric characters. The characters are often grouped so that, for example, a first group indicates a first characteristic, a second group indicates a second characteristic, and so on. For example, board 10 of FIG. 1 includes examples of such operational characteristic identifiers 20a, 20b, 20c, and 20d. The characters also may be highlighted or emphasized to group certain characters, thereby giving further meaning to their intended identification.
In the prior art, one method of forming operational characteristic identifiers labeled 20a-20d uses an ink process. Such a method is long known for other types of imprinting, such as is often used for creating nameplates, or in children's games or the like. Particularly, in the prior art, a human operator typically selects individual or grouped rubber stamps which combine to form the desired indication for the circuit board's operational characteristics. The operator cuts the rubber stamps from a strip, or chooses them from a larger group which includes the desirable stamp(s). The chosen stamp(s) are combined in the desirable order and affixed to the end of a stamping peg. Thereafter, the end of the stamping peg, and consequently the chosen rubber stamps, are depressed against an ink pad. Next, the inked end, and stamps, are pressed against the circuit board. Consequently, an ink impression remains on the circuit board and reflects the rubber stamps chosen by the operator.
The prior art process suffers many drawbacks. For example, the ink impression may not be evenly applied to the circuit board and, hence, may be illegible. As another example, the ink is subject to smearing while it remains wet, or may become obscured during subsequent handling of the circuit board. As still another example, the process of selecting stamps is subject to human error; namely, the operator may choose the wrong stamp(s), or place the stamp(s) in an inaccurate order. Such operator error could result in the circuit board being mistakenly used in the wrong environment or equipment, thereby causing failure of such equipment.
It is therefore an object of the present invention to provide an apparatus and method for constructing a circuit board having an improved identification marking apparatus.
It is a further object of the present invention to provide such an apparatus and method for minimizing human error and/or human resources involved in identifying the operational characteristics of a circuit board.
It is a further object of the present invention to provide such an apparatus and method for quickly affixing an identifier or identification marking to a circuit board.
It is a further object of the present invention to provide such an apparatus and method for accurately, consistently and efficiently affixing an identifier or identification marking to a circuit board,
It is a further object of the present invention to provide such an apparatus and method for permitting automatic verification that the correct identifier is located on a given circuit board.
It is a further object of the present invention to provide such an apparatus and method for permitting automatic determination of a circuit board's operational characteristics by electrically testing the identification component(s) on the board,
Still other objects and advantages of the present invention will become apparent to those of ordinary skill in the art having references to the following specification together with its drawings.